1. Field of the Invention
The invention relates to an automobile headlight, and more particularly to a headlight having three lamps, i.e., a dipped-beam lamp (or low beam lamp), a main-beam lamp (or high beam lamp), and an auxiliary lamp, continuously arranged in a horizontal row.
2. Related Art
Three lamp headlights having a dipped-beam lamp, a main-beam lamp and an auxiliary lamp having been proposed. A triple headlight is characterized as integrating three lamps including both beam lamps and a fog lamp or other auxiliary lamp with one another in a row in order to meet design requirements, parts reducing requirements, and the like. For example, FIG. 7 shows a headlight having a dipped-beam lamp LL, a main-beam lamp HL, and a fog lamp FL arranged from the outer part to the inner part of an automobile with respect to a headlight body 101. A reflector 102 integrating reflectors 103, 104 for both beam lamps LL, HL, and a reflector 105 for the fog lamp, are juxtaposed within the headlight body 101. In addition, bulbs 106, 107, 108 are provided. Further, a lens 109 is attached to the front of the headlight body 101. The triple headlight is thus formed.
In the thus constructed triple headlight, the possibility of using a discharge bulb having high luminance and good color rendering for the dipped-beam lamp LL has been studied. The discharge bulb requires a lighting circuit for lighting itself. If the lighting circuit is constructed of a metal case and arranged immediately behind the dipped-beam lamp, the weight balance of the headlight is impaired, because the lighting circuit includes a booster transformer and other components that make it relatively heavy. In addition, since there is only a small space between the back of the headlight and the automobile body at the outer part of the headlight, it is difficult to reserve space for arranging the lighting circuit, which in turn makes it difficult to design the headlight.
Thus, the lighting circuit 110 is arranged substantially in the middle of the headlight body 101 toward the back, so that the above noted weight balance and arranging space problems are overcome. However, with this arrangement, a longer cord 111 must be provided for connecting the discharge bulb 106 in the dipped-beam lamp LL at the outer part of the headlight to the lighting circuit 110. Since high voltage is supplied through this cord 111, electromagnetic waves are radiated to produce electric noise which interferes with the instruments in the automobile, e.g., causing noise in the radio, the car telephone, and the like. Further, if the lighting circuit 110 is arranged toward the inner part of the headlight for some reason, the cord 111 becomes extremely long, aggravating the electromagnetic problems.
Further, in the aforementioned triple headlight, the fog lamp FL that is less frequently used for ordinary city cruising is arranged toward the inner part, and the dipped-beam lamp LL that is more frequently used is arranged toward the outer part so as to be remote from the fog lamp. Therefore, when only the dipped-beam lamp LL is lit and the fog lamp FL is not lit during night driving, the headlight is not illuminated as a whole, i.e., only the outer portion is illuminated, which in turn impairs the external appearance of the headlight.